These functions provide access to the Program Priority Register (PPR)
on the Power architecture.
The PPR is a 64-bit register that controls the program's priority.
By adjusting the PPR value the programmer may improve system
throughput by causing system resources to be used more efficiently,
especially in contention situations. The available unprivileged
states are covered by the following functions:
* __ppc_set_ppr_med() sets the Program Priority Register value to
medium (default).
* __ppc_set_ppr_very_low() sets the Program Priority Register value
to very low.
* __ppc_set_ppr_low() sets the Program Priority Register value to
low.
* __ppc_set_ppr_med_low() sets the Program Priority Register value
to medium low.
The privileged state medium high may also be set during certain time
intervals by problem-state (unprivileged) programs, with the
following function:
* __ppc_set_ppr_med_high() sets the Program Priority to medium high.
If the program priority is medium high when the time interval expires
or if an attempt is made to set the priority to medium high when it
is not allowed, the priority is set to medium.

The functions __ppc_set_ppr_med(), __ppc_set_ppr_low() and
__ppc_set_ppr_med_low() are provided by glibc since version 2.18.
The functions __ppc_set_ppr_very_low() and __ppc_set_ppr_med_high()
first appeared in glibc in version 2.23.

The functions __ppc_set_ppr_very_low() and __ppc_set_ppr_med_high()
will be defined by <sys/platform/ppc.h> if _ARCH_PWR8 is defined.
Availability of these functions can be tested using #ifdef_ARCH_PWR8.

This page is part of release 5.00 of the Linux man-pages project. A
description of the project, information about reporting bugs, and the
latest version of this page, can be found at
https://www.kernel.org/doc/man-pages/.
GNU C Library 2017-09-15 __PPC_SET_PPR_MED(3)